REST Client is a method or a tool to invoke a REST service API that is exposed for communication by any system or service provider. For example: if an API is exposed to get real time traffic information about a route from Google, the software/tool that invokes the Google traffic API is called the REST client
Like Insomnia & Postman.

In the first phase, I designed the graphical user interface (GUI)
In the second phase, I designed the console interface (CurlHttp) In the last phase, I connected the second phase to the first phase (HttpRequest)

CurlHttp: java -jar "CompiledJarFile.jar" --help